Beam stopper for a radiotherapy device

Abstract

A radiotherapy system (220, 320) comprises a first rotary support apparatus (204, 304) configured to support a radiation beam source (200, 300) and to cause a radiation beam source (200, 300) to rotate about a rotation axis (218, 318, 518), a second rotary support apparatus (214, 314, 414, 514) and a radiation shield (202, 302, 402, 502) mounted to the second rotary support apparatus (214, 314, 414, 514). The second rotary support apparatus (214, 314, 414, 514) is configured to cause the radiation shield (202, 302, 402, 502) to rotate about the rotation axis (218, 318, 518).

The invention claimed is: 
     
       1. A radiotherapy system comprising:
 a first rotary support apparatus configured to support a radiation beam source and to cause the radiation beam source to rotate about a rotation axis; 
 a second rotary support apparatus; 
 a radiation shield mounted to the second rotary support apparatus, wherein the second rotary support apparatus is configured to cause the radiation shield to rotate about the rotation axis, and wherein the second rotary support apparatus includes one of: 
 a rotatable gantry, wherein the radiation shield is fixed to the rotatable gantry, and wherein the rotatable gantry is configured to rotate about the rotation axis passing through a center of the rotatable gantry; 
 two concentric ring gantries with concentric central bores centered on the rotation axis, wherein a first end and an opposing second end of the radiation shield are fixed to each of the two concentric ring gantries, and wherein the two concentric ring gantries are configured to rotate about the rotation axis to cause the radiation shield to rotate about the rotation axis; or 
 one or more curved guides, wherein the radiation shield is slidably mounted to the one or more curved guides to travel along the one or more curved guides. 
 
     
     
       2. The radiotherapy system of  claim 1 , further comprising:
 the radiation beam source mounted to the first rotary support apparatus. 
 
     
     
       3. The radiotherapy system of  claim 1 , wherein the radiation shield is configured to be capable of rotating about the rotation axis independently of a rotation of the radiation beam source. 
     
     
       4. The radiotherapy system of  claim 1 , wherein the radiation shield is configured to rotate about the rotation axis in synchrony with a rotation of the radiation beam source. 
     
     
       5. The radiotherapy system of  claim 1 , further comprising:
 a rotary drive system configured to drive the first rotary support apparatus that rotates at least one of the radiation beam source or the second rotary support apparatus radiation shield about the rotation axis. 
 
     
     
       6. The radiotherapy system of  claim 1 , wherein a rotation of the radiation beam source about the rotation axis causes the radiation shield to travel along a first curved path, the first curved path being along at least a portion of a circumference of a circle centered on the rotation axis, and wherein a rotation of the radiation shield about the rotation axis causes the radiation shield to travel along a second curved path, the second curved path being along at least a portion of a circumference of a circle centered on the rotation axis. 
     
     
       7. The radiotherapy system of  claim 1 , further comprising:
 a fixed gantry with a central bore operable to receive the rotatable gantry of the second rotary support apparatus, wherein the rotatable gantry is rotatably mounted within the central bore of the fixed gantry and is configured to rotate with respect to the fixed gantry. 
 
     
     
       8. The radiotherapy system of  claim 1 , wherein the rotatable gantry is a drum gantry, and wherein the radiation shield is fixed inside the drum gantry. 
     
     
       9. The radiotherapy system of  claim 1 , wherein the radiation shield is fixed to an arm of the rotatable gantry extending outward from the rotatable gantry in an axial direction parallel to the rotation axis. 
     
     
       10. The radiotherapy system of  claim 1 , wherein the two concentric ring gantries are connected by one or more supporting beams that provide structural support to the two concentric ring gantries. 
     
     
       11. The radiotherapy system of  claim 1 , wherein each of the one or more curved guides is a circular ring centered on the rotation axis. 
     
     
       12. The radiotherapy system of  claim 1 , wherein each of the one or more curved guides forms a semicircle centered on the rotation axis. 
     
     
       13. The radiotherapy system of  claim 1 , wherein each of the one or more curved guides forms an arc of a circle centered on the rotation axis. 
     
     
       14. The radiotherapy system of  claim 1 , further comprising:
 a second radiation shield slidably mounted to the one or more curved guides to travel along the one or more curved guides. 
 
     
     
       15. The radiotherapy system of  claim 2 , wherein the radiation beam source is configured to emit a beam of radiation directed towards the rotation axis. 
     
     
       16. The radiotherapy system of  claim 4 , further comprising:
 a rotary coupling system configured to mechanically couple the rotation of the radiation beam source to the rotation of the radiation shield, wherein at least one of a rotation of the radiation shield drives a rotation of the radiation beam source or the rotation of the radiation beam source drives a rotation of the radiation shield using the rotary coupling system. 
 
     
     
       17. The radiotherapy system of  claim 5 , further comprising:
 a control system configured to control the rotation of the radiation shield to cause the radiation shield to maintain a fixed position relative to the radiation beam source as the radiation beam source rotates about the rotation axis. 
 
     
     
       18. The radiotherapy system of  claim 17 , wherein the control system is configured to control the rotation of the radiation shield such that the radiation shield is always in a path of a radiation beam emitted from the radiation beam source as the radiation beam source rotates about the rotation axis. 
     
     
       19. The radiotherapy system of  claim 17 , wherein the control system is configured to control the rotation of the radiation shield such that the radiation shield is always diametrically opposed to the radiation beam source as the radiation beam source rotates about the rotation axis. 
     
     
       20. The radiotherapy system of  claim 17 , wherein the radiotherapy system further comprises:
 a first rotary drive system configured to drive a rotation of the radiation beam source; and 
 a second rotary drive system configured to drive rotation of the radiation shield; 
 wherein the control system is configured to control one or both of the first rotary drive system and the second rotary drive system. 
 
     
     
       21. The radiotherapy system of  claim 12 , further comprising:
 a fixed radiation shield extending between opposing ends of the one or more curved guides. 
 
     
     
       22. The radiotherapy system of  claim 14 , wherein the first shield apparatus is slidably mounted on a first portion of the one or more curved guides, and the second shield apparatus is slidably mounted on a second portion of the one or more curved guides. 
     
     
       23. The radiotherapy system of  claim 22 , wherein a position of the second shield apparatus on the second portion of the one or more curved guides is a reflection of a position of the first shield apparatus on the first portion, wherein the reflection is defined by a line of symmetry passing between the first and second portions of the one or more curved guides and through the rotation axis. 
     
     
       24. A method of controlling a rotation of a radiation shield in a radiotherapy system:
 rotating a radiation beam source about a rotation axis, wherein the radiation beam source is mounted on a first rotary support apparatus and is configured to emit a radiation beam; and 
 rotating a radiation shield about the rotation axis, wherein the radiation shield is mounted on a second rotary support apparatus separate from the first rotary support apparatus, wherein the rotation of the radiation shield is synchronized with the rotation of the radiation beam source, and wherein the second rotary support apparatus includes one of:
 a rotatable gantry, wherein the radiation shield is fixed to the rotatable gantry, and wherein the rotatable gantry is configured to rotate about the rotation axis passing through a center of the rotatable gantry; 
 two concentric ring gantries with concentric central bores centered on the rotation axis, wherein a first and an opposing second end of the radiation shield are fixed to each of the two concentric ring gantries, and wherein the two concentric ring gantries are configured to rotate about the rotation axis to cause the radiation shield to rotate about the rotation axis; or 
 one or more curved guides, wherein the radiation shield is slidably mounted to the one or more curved guides. 
 
 
     
     
       25. The method of  claim 24 , further comprising:
 rotating the radiation shield about a second axis to maintain the radiation shield in a path of the radiation beam.